Defibering apparatus for paper making stock

ABSTRACT

A deflaker for use in defibering coarse paper making stock includes a rotor and stator having frusto-conical working faces, each of which has therein one or more circumferential rows of angularly spaced pockets separated by axially extending land areas and with a circumferential land between adjacent rows of pockets, the proportions and arrangement of the parts being such that the stock is forced to travel back and forth between rotor and stator pockets as it passes through the working zone. The inlet chamber in which the rotor and stator operate is of substantially larger diameter to provide outlying space to which high specific gravity contaminant materials are directed by the centrifugal force generated by the rotor, and this action is enhanced by a cover plate on the inlet end of the rotor which has the dual function of defining with the adjacent end wall of the stator an entry slot to the working zone, and of developing additional centrifugal force further tending to prevent high specific gravity contaminant materials from reaching this inlet slot. The working faces of the rotor and stator are axially symmetrical so that the rotor can be driven in either direction to double the working life of these elements, and when it is necessary to remove and replace any of the working elements, this can be done without disturbing any piping connections by simply removing a cover plate which forms one wall of the inlet chamber.

BACKGROUND OF THE INVENTION

This invention relates to apparatus of the type commonly known as"deflakers" which are used in the preparation of paper making stock,especially from waste paper materials of widely varying characteristics.

Deflakers are often used to perform a defibering operation on relativelycoarse stock which has either been extracted from a pulper withoutscreening, or which has been rejected by a relatively coarse screenafter extraction from a pulper. Such stock can therefore be expected tocontain not only a high proportion of usable but still undefibered papermaterial, but also substantial quantities of reject materials such asplastic, tramp metal such particularly as staples, screws, wire, nutsand bolts, and other hard contaminant materials.

A significant problem which has been encountered by deflakers of theprior art has been their inability to handle successfully stock whichcontains tramp metal. More specifically, the prior art deflakers haveshown a tendency to be self-destructive in that they will accept stockcontaining tramp metal, but their filling or tackle becomes so damagedin attempting to disintegrate the metal that it becomes useless forfurther defibering action.

Other practical disadvantages of prior art deflakers have included thecost of their filling or tackle, its tendency to wear to the point ofunacceptably low effectiveness, and the time and effort required for itsreplacement, which commonly includes the necessity of disconnecting andreconnecting one or both of the inlet and outlet pipe lines. Further,prior art deflakers often permit stock to flow through grooves in theworking face of the rotor or stator without entering the high sheardefibering zone between those faces, which results in poorly defiberedstock.

SUMMARY OF THE INVENTION

The primary object of this invention is to provide a deflaker which willhave high defibering efficiency, in which there will be minimalpossibility for stock to bypass the working zone, and especially whichwill prevent tramp metal from entering the working zone and therebyprotect itself against self-destruction.

An additional object of the invention is to provide such a deflakerwherein the working elements are relatively low in cost, from thestandpoint of both manufacturing costs and service life, which can beremoved and replaced quickly and easily without the necessity ofdisconnecting any pipes, and wherein the rotor can be operatedselectively in either direction with equal effectiveness and willtherefore provide two sets of working edges which can be used in turnafter the first set has become worn, or on a more frequent basis toprolong the wear life of the working edges.

These objectives are achieved in accordance with the invention bydeflaking apparatus wherein the housing encloses an inlet chamber ofrelatively large dimensions in comparison with the working elementswhich operate therein and comprise a rotor and a stator havingcomplementary frusto-conical working faces. Each of these faces isprovided with one or more circumferential rows of pockets spaced fromeach other to provide an extending land area between adjacent pockets,and the edges of each of these land areas on the rotor extend generallylengthwise of the rotor.

The apparatus is preferably provided with a reversible drive so thateach set of land edges can operate selectively as leading edges. Whenthe rotor is running in one direction, these leading edges tend to beprogressively rounded, but at the same time, the trailing edges tend tobecome sharpened. In fact, if relatively soft metals are used in therotor, a burr will form on the trailing edges which is relativelyfragile but sharp. Preferred results are obtained by relatively frequentchanging of the direction of rotation of the rotor, thereby utilizingthe beneficial effects of trailing edge sharpening or reconditioning andcorrespondingly significantly prolonging wear life and constantoperating efficiency.

Many variations of the patterns of the working faces are possible, andin a preferred embodiment, each of the pockets in the rotor and statorhas generally axially extending side walls and one generally radiallyextending end wall, which is the back wall in the rotor and the frontwall in the stator. The peripheries of these end walls and theintervening areas of the working face combine to form circumferentiallands on both the rotor and stator. The axial dimensions of the rotorand stator themselves and of the pockets in their working faces are ofpredetermined relationship such that each of these circumferential landsis in opposed relation with a row of pockets in the other workingelement, thereby forcing the stock to travel back and forth betweenpockets in the rotor and stator as it passes through the working zonefrom the inlet port to the outlet port of the housing.

The use of frusto-conical working faces contributes an additionaloperational feature of the apparatus in that relative axial adjustmentof the rotor and stator provides for corresponding adjustment of theworking clearance between their working faces. This enables the operatorto compensate from time to time for wear of the working elements so thatthe apparatus can produce uniformly treated pulp over long periods oftime in spite of wear. Also, this enables the operator to compensatewhen more or less easily defiberable material is fed to the apparatus.

Special provision is made in accordance with the invention forminimizing the possibility for access by tramp metal and other highspecific gravity materials to the working zone. This result isaccomplished in part by the relatively large diametral dimensions of theinlet chamber as compared with the smaller ends of the rotor and statorwhich extend into this chamber. The centrifugal forces generated byrotation of the rotor have a natural tendency to cause high specificgravity materials to migrate to the outer wall of the inlet chamber foreasy removal rather than to remain in the flow of stock which enters theworking zone.

Positive protection against tramp metal and the like is provided by afront end cap on the rotor which includes a peripheral skirt portion ofgreater diameter than the inner diameter of the smaller end of thestator and thereby forms with the front end of the stator acircumferential slot of relatively small axial dimension through whichall stock must pass in order to enter the working zone. This capenhances the centrifugal action which causes high specific materials tomove outwardly away from this inlet slot, and the dimensions of the slotitself further discourage the entry of overlarge pieces. The inletchamber is provided with one or more clean-out ports from which suchreject materials can be easily removed from time to time.

An additional feature of the invention, which is contributed to by therelative dimensions of the inlet chamber and of the rotor and stator, isthe case of replacement of these working elements. The end of thehousing which encloses the inlet chamber is provided with a cover plateenclosing an opening larger in diameter than the rotor and stator, sothat when this cover plate is removed, the rotor and stator can bedismounted, taken out through the resulting opening, and replaced withminimum down time and without requiring disconnection of any pipingleading to or from the apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical axial section through deflaking apparatus inaccordance with the invention;

FIG. 2 is an end view looking from left to right in FIG. 1;

FIG. 3 is an end view looking from right to left in FIG. 1;

FIG. 4 is a fragmentary plan view of the drive end of the apparatusshown in FIG. 3;

FIG. 5 is an enlarged fragment of FIG. 1;

FIG. 6 is a fragmentary view of the working face of the rotor of FIGS. 1and 5;

FIG. 7 is a section on the line 7--7 of FIG. 6;

FIG. 8 is a diagram identifying reference angles for describing thegeometry of the pockets in the rotor;

FIG. 9 is a fragmentary view looking axially toward the working face ofthe stator from right to left in FIG. 5;

FIG. 10 is a fragmentary view of the working face of the stator taken atright angles to FIG. 9;

FIG. 11 is a fragmentary and somewhat diagrammatic axial section similarto FIG. 5 and illustrating the operation and working relation of therotor and stator.

FIG. 12 is a fragmentary view similar to FIG. 1 and taken on the line12--12 in FIG. 13 to show a modified construction; and

FIG. 13 is an end view looking from left to right in FIG. 12.

FIG. 14 is a view similar to FIG. 6 and showing a modified arrangementof pockets in the working face of a rotor in accordance with theinvention;

FIG. 15 is a view similar to FIG. 14 and showing another modifiedarrangement of rotor pockets;

FIG. 16 is a fragmentary and somewhat diagrammatic view showing workingelements in accordance with the invention wherein both the rotor andstator include a pair of working faces of substantially different radialdimensions;

FIG. 17 is a fragmentary and somewhat diagrammatic view showing anothermodification of the invention wherein the rotor has working faces atboth ends thereof each cooperating with a pair of stators;

FIG. 18 is a view similar to FIG. 17 and showing the reversearrangements of FIG. 17 wherein the larger ends of the working faces ofthe rotor are at the opposite ends of the rotor body;

FIG. 19 is a fragmentary sectional view showing a form of rotor andstator in accordance with the invention wherein the pockets in theworking faces are milled to an arcuate contour in axial section; and

FIG. 20 is a similar view showing another pocket contour;

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The main body 10 of the deflaking apparatus includes at one end anessentially cylindrical housing portion 11 enclosing the inlet chamber12 to which the stock is delivered through the inlet port 13 at the topof the housing 11. The annular outlet chamber 15 at the back of thehousing 11 is similarly provided with an outlet port 16 at the top, andat the bottom of the chamber 12 is a pair of clean-out ports 17. Theremainder of the main body 10 beyond the housing portion 11 comprisesthe supporting and adjusting structure for the rotor drive shaft 20, asdescribed in detail hereinafter.

The inlet and outlet chambers 12 and 15 within housing 11 are separatedby the working elements of the apparatus, which are the frusto-conicalrotor 22 on shaft 20 and the complementary stator 25. The stator 25 issecured within the housing 11 by three angularly spaced clamps 26 ofL-shaped section and screws 27 threaded into a mounting ring 28 weldedwithin the housing 11, one of these clamps 26 being shown in FIG. 5 andthe others being equidistant therefrom and from each other. The rotor 22is mounted on the front end of the shaft 20 by a hub 30 keyed on the endof the shaft and held in place by a retainer plate 31 and screw 32. Thehub 30 includes a flange 33 at its inner (larger) end, and the rotor 22is clamped against this flange by means of the end cap 35 which ismounted on the hub 30 by a series of screws 36.

Referring to FIGS. 6 and 7, the frusto-conical working face of the rotor22 is provided with two circumferential rows of angularly spaced pocketsseparated by axially and circumferentially extending land areas. Thepockets 40 in the front row are separated by land areas 41 in equallyspaced relation around the small end of the rotor. Each of these pockets40 has side walls 42 which extend generally axially of the rotor, and aback wall 43 extending generally radially of the rotor. This arrangementprovides edges 44 along opposite sides of each of the land areas 41.Iadd., but the bottom wall 56 of each pocket extends from theassociated back wall 43 to the surface of the rotor so that the backwall 43 constitutes the only end wall of the pocket.Iaddend..

The outer peripheries of the back walls 43 meet the working face of therotor and form therewith a circumferential land 45 which separates therow of pockets 40 from the row of pockets 50. These pockets 50 aresimilar to the pockets 40 in shape but smaller in all their dimensions,and they are similarly separated by axial land areas 51. The side walls52 of the pockets 50 also extend generally axially, and each pocket hasa generally radially extending back wall 53. The working edges 54 of theland areas 51 correspond to the similar working edges of the land areas41, and the peripheries of the back walls 53 meet the working face ofthe rotor and form therewith a second circumferential land 55 around thelarge end of the rotor.

As best shown in FIGS. 8 and 11, the bottom walls 56 and 57 of thepockets 40 and 50 extend generally parallel with the axis of the rotor,or at a relatively small angle with respect thereto, and this results inmaking each pocket of increasing depth from front to back, with themaximum depth being along its back or end wall. Further, the pockets 40and land areas 41 are fewer in number and individually wider than thepockets 50 and land areas 51, which provides a correspondingly greaternumber of working edges 54 around the larger end of the rotor. As anexample of satisfactory dimensions, a rotor having a maximum diameter of19 inches at the outer edge of the land 55 may have 54 land areas 41each approximately 0.40 inch in width, and 72 land areas 51 eachapproximately 0.30 inch in width.

The geometric configuration of each pocket 40 and 50 can be describedgenerally in terms of several angles with reference to FIG. 8, wherein arepresents 1/2 of the included angle of the frusto-conical working faceof the rotor, b is the angle defined by the bottom wall 56 of a pocket40 and a line 58 parallel with the axis 59 of the rotor, and hence alsowith the axis 59, and the axis of the rotor, and c is the angle definedby the pocket back wall 43 and the rotor axis. Also, referring to FIG.6, d is the included angle of the pocket side walls 42. For good designin accordance with the invention the relations of these angles shouldbe:

    ______________________________________                                        Angle   Range            Preferred                                            ______________________________________                                        a       15° to 75°                                                                       20° to 30°                             b       Smaller than c   3° to 6°                                       and greater than 0°                                            c       Greater than a but                                                                             At least 30° greater                                  not more than 120°                                                                      than a to 90°                                 d       0° to approximately                                                                     3° to 15°                                      60°                                                            ______________________________________                                    

The conditions to be considered in selecting a cone angle for the rotorworking face include the fact that outside of the indicated range,pocket depth is so small that the cross section through which the slurryflows becomes impractically small. The preferred included angle of 40°to 60° gives sufficient pocket cross section and does not result inexcessive diameter increase from the feed end of the rotor to itsdischarge end, which is desirable because excessive diameter increaseproduces greater pressure buildup and results in excessive axial thrustvalues. Note also that as shown, it is convenient to connect the bottomand back walls of each pocket by a smoothly curved portion so that theangular conditions listed above are fulfilled near the surface of therotor.

The stator 25 has a frusto-conical working face which is in all materialrespects complementary to that of the rotor 22. Referring to FIGS. 9-10it includes a front row of pockets 60 separated by land areas 61 andeach pocket having side walls 62, which extend generally axially of thestator, and a front wall 63 which extends generally radially of therotor. The land areas 61 have working edges 64, and there is acircumferential land 65 at the small end of the stator .Iadd., but thebottom wall of each stator pocket extends from its associated front wall63 to the surface of the stator so that the front wall 63 constitutesthe only end wall of the pocket.Iaddend..

The pockets 70 in the second row are smaller in all dimensions than thepockets 60 and are similarly separated by land areas 71. The side walls72 of each pocket 70 extend generally axially toward the large end ofthe stator from the generally radially extending front wall 73. The landareas 71 have working edges 74 like those on the other land areas, andthere is a circumferential land 75 which separates the two rows ofpockets and is composed of the exposed peripheries of the pocket walls73 and the intervening portions of the working face of the stator. Theconfiguration of each of the pockets 60 and 70 should conform togeometric limitations corresponding to those discussed for the rotorpockets 40 and 50.

FIG. 11 illustrates somewhat diagrammatically the working relation ofthe working faces of the rotor 22 and stator 25. The parts are soproportioned that when these working faces are in proper workingrelationship, with a close clearance therebetween, the small end of therotor projects outwardly from the stator, the several circumferentiallands are in axially staggered relation with each other, and each ofthese lands is in radially opposed relation with a row of pockets in thecomplementary working element. As a result, the stock must enter theworking zone through the shallow ends of the rotor pockets 40, and sinceit cannot advance axially in any pocket 40 beyond its rear wall 43, itmust transfer into the stator pockets 60, but it cannot travel in thembeyond the circumferential land 75 and must therefore enter a rotorpocket 50. Once again, axial flow in the pockets will be interrupted bythe pocket back walls 53, causing a further transfer of the stock to thestator pockets 70 before it reaches the outlet chamber 15.

The passage of stock through the working zone as summarized in thepreceding paragraph is illustrated by the series of arrows in FIG. 11.It will be understood, however, that it will not be possible for thestock to follow this path in a continuous axial direction. Instead, thesolid material in the stock will be subjected to repeated workingbetween the surfaces of opposed land areas, and especially to theworking action of the rotor pocket edges 44 and 54 as they travel pastsuccessive stator pockets, the land areas therebetween, and especiallythe land edges 64 and 74 on the stator. The stock is thereforeeffectively prevented from bypassing the working zone by following onlyopen channels through successive pockets, and this result is alsocontributed to by the variation in the size and number of the pockets inthe successive rows in both the rotor and stator.

As previously noted, the land edges 44, 54, 64 and 74 are particularlyactive in the defibering operations of the apparatus, and it necessarilyfollows that in due course, they may become worn or blunted. With therotor and stator pockets so formed that these land edges extendgenerally axially, or at equal but opposite angles to the axis, however,it is then necessary only to reverse the direction of the rotor whenthis has occurred, or preferably to reverse the drive at frequentintervals and thereby to obtain the self-sharpening action previouslydescribed. This is easily done by providing the rotor shaft 20 with anysuitable conventional reversible drive, or a reversing switch for astandard motor, as indicated diagrammatically at 77, thus more thandoubling the service life of a single set of working elements. Inaddition to this service life advantage, the rotor and stator of theinvention offer the further practical advantage that they can be castwithout expensive coring or readily fabricated from blanks of stainlesssteel or other desired metal which can be appropriately hardened.

The action of the invention in minimizing the possibility that trampmetal and other high specific gravity metals can reach the working zoneis contributed to by a number of factors or features. In the firstplace, with the front end of the rotor substantially smaller than theinner diameter of the inlet chamber 12, e.g. a minimum diameter of 13inches across the bottoms of the pockets 40 as compared with an innerdiameter of 24 inches for the chamber 12, the rotation of the rotoralone will develop centrifugal force which will have a strong tendencyto cause the high specific gravity materials to migrate toward the wallof the housing 11 rather than to remain sufficiently near the center ofthe chamber to be in position to enter a rotor pocket.

More positive assurance against the access of heavy materials to therotor pockets 40 is provided by the rotor cap 35, which is afrusto-conical member of sufficiently greater base diameter than thesmall end of the rotor to form an annular skirt 80 radially overlyingthe inlet ends of the rotor pockets 40. As shown, this skirt 80 is ofsufficiently greater diameter than the inner diameter of the small endof the stator, e.g. 1 inch or more, that it forms with the outer endwall of the stator a circumferential slot 81 through which stock mustpass in order to enter a rotor pocket 40, preferred results having beenobtained with this slot having an axial dimension of approximatelythree-fourths inch. In addition, the rotation of the rotor cap 35develops centrifugal force which will be most effective against anyheavy materials near its outer periphery, and which will thus augmentthe action of the rotor in causing such heavy materials to travel to theouter wall of the housing 11, and ultimately to the trough 82 extendingbetween the cleanout ports 17.

The relative dimensions of the rotor 22 and the housing 11 noted abovealso contribute significantly to another feature of the invention,namely the ease of replacement of the working elements. As shown inFIGS. 1 and 2, the front wall of the housing 11 is formed by a circularcover plate 85 removably secured by screws 86 to a ring 88 welded insidethe housing 11. Removal of this cover plate exposes the entire interiorof chamber 12 through the resulting opening, which is larger in diameterthan both the rotor and stator. The removal of the latter forreplacement through this opening therefore requires only the release ofthe screws 36 mounting the rotor cap 35 on hub 30 and of screws 27holding the stator clamps 26 in place, since the hub 30 remains on theshaft. It is especially advantageous that this servicing operation doesnot require any interference with the pipe or hose connected to eitherof the ports 13 and 16, except other than to close whatever valve maycontrol each such pipe or hose.

The invention also provides for relative adjustment of the rotor 22 andstator 25 to the desired working clearance of their working faces, thepreferred range of which has been found to be 0.01 to 0.15 inches, with0.03 inches providing optimum stable operation. Referring to FIGS. 1 and3-4, the shaft 20 is supported by a thrust bearing 90 and radial bearing91 in a tubular housing 92 which is in turn supported for controlledaxial adjustment in a pair of inner and outer wall members 94 and 95welded within the portion of main body 10 beyond the housing 11. Anadjusting plate 99 is mounted on the outer end of the bearing housing 92by a plurality of screws 96 and is provided with means for effecting itscontrolled adjustment with respect to the wall 95.

More specifically, an adjusting screw 100 is threaded through theadjusting plate 99 and passes freely through a bore in the wall 95. Nuts101 and 102 are threaded on the screw 100 on either side of the wall 95,and it will be seen that by releasing either of these nuts andtightening the other, the screw 100 can be pushed or pulled through thewall 95 and thereby cause corresponding movement of the adjusting plate99, the bearing housing 92 and the shaft 20. An indexing screw 105 isfixed with its head on the inner side of the adjusting plate 99 to forma stop limiting inward movement of plate 99 with respect to wall 95beyond the position in which the working faces of the rotor and statorare just out of frictional contact.

FIGS. 12 and 13 show a modified construction wherein the cover plate 110for the housing portion 111 incorporates baffle means for guiding thestock to the center of the inlet chamber 112 from the inlet port 113. Anannular partition plate 115 having a central opening 116 is mounted onthe inside of the cover plate 110 by a plurality of radially extendingwebs 117 and a central tubular member 120. The webs 117 each have alarge center hole 121 therein, and there is a similar hole 122 in thelower side of the tubular member 120.

With this construction, stock entering through the inlet port 113 canreach the interior of the inlet chamber 112 only by passing through atleast two of the holes 121, the hole 122 and the opening 116. It istherefore virtually impossible for heavy specific gravity material toreach the inlet chamber, and if any such material, e.g. tramp metal,should be trapped on the upper side of the tubular member 120, it iseasily removed by taking off this cover plate assembly from time to timeand dumping such accumulated reject. This cover plate construction alsooffers the further practical advantage of reducing the inlet pressurerequirements, which would otherwise be determined by the radial pressurebuildup resulting from rotation of the stock in the inlet chamber, butthis rotational effect cannot influence the entering flow until thestock has passed through the opening 116.

The working members of the apparatus shown in FIG. 12 are identifiedgenerally at 125 and are of the same construction described inconnection with FIGS. 1-11. However, FIG. 12 does show a modifiedarrangement of discharge port comprising an elbow 130 mounted on theback wall 131 of that portion of the housing enclosing the outletchamber 135. This part of the housing, however, could be constructed inthe same manner shown in FIG. 1.

FIGS. 14-20 illustrate a variety of modifications of the apparatus ofFIGS. 1-13 which also embody the principles of the invention. Thus FIG.14 shows a fragment of a rotor 140 having two peripheral rows of pocketsin its working face but with each row consisting of alternatingrelatively long and relatively short pockets. More specifically, the rowof pockets adjacent the smaller end of the rotor comprise relativelylong pockets 141 alternating with relatively short pockets 142, and theother row similarly comprises relatively long pockets 143 alternatingwith relatively short pockets 144. The rotor 140 also hascircumferential lands 145 adjacent its larger end and between the tworows of pockets of its working face, and each pocket should conformgenerally to the same geometry disclosed by the above in connection withFIG. 8. The stator with which the rotor 140 is used will preferably havea complementary pattern of rows of alternately long and short pockets inthe working face thereof.

FIG. 15 shows a modified rotor 150 generally similar to the rotor 140 inthat the row of pockets adjacent the smaller end thereof comprisesalternating long pockets 151 and short pockets 152. The rotor 150 alsoincludes a second circumferential row of pockets 153 shown as ofessentially the same dimensions as a long pocket 151 and in axiallyuniformly spaced relation therewith. Since this arrangement would leavea relatively wide land area between alternate pockets 153 and the largerend of the rotor, an additional relatively short pocket 154 is providedin each such space. The rotor 150, however, still includescircumferential lands 155 at the larger end thereof and between the tworows of pockets thereon. The stator with which this rotor 150 is usedwill preferably have a complementary pattern of pockets in its workingface.

FIG. 16 shows a modified construction of working elements in accordancewith the invention wherein the rotor 160 has a frusto-conical workingface 161 of relatively small average radius adjacent the inlet endthereof and a working face 162 of substantially larger average radiusadjacent its discharge end. The working face 161 has pockets 163 thereinsimilar to the pockets 40 as already described. There is also an annularland 165 extending radially from the larger end of the working face 161to the smaller end of the working face 162. The pockets 166 in theworking face 162 are also similar in geometry and distribution to thepockets 163, and there is therefore a circumferential land 167 aroundthe larger end of the working face 162.

The stator 170 in FIG. 16 is shown as essentially complementary to therotor 160, in that it has a small radius working face comprising similarpockets 173, and land 174, a radial land 175, and a large radius workingface comprising pockets 176 and a land 177 all arranged in complementaryfashion to the corresponding portions of the rotor 160. It should alsobe understood that either or both of the working faces of the rotor andstator can have a plurality of rows of pockets therein similarly to therotor 22 and the stator 25, and also that the dimensions and arrangementof all of these pockets are subject to variation such as described inconnection with FIGS. 14-15. Similarly the rotor 160 will preferably beprovided with an end cap similar to and for the same purpose as the endcap 35.

In the modification shown in FIG. 17, the rotor 200 is double ended andcooperates with a pair of stators 202 in a housing 205 having an inletchamber 206 at each end thereof provided with its own inlet port 207,and a centrally located annular discharge chamber 208 provided with adischarge port 209. The rotor 200 includes a frusto-conical working face211 at one end thereof, a similar frusto-conical working face 212 at theother end, and a cylindrical central surface 213. Each of the workingfaces 211 and 212 is shown as of a construction generally similar to therotor 22 as already described.

The two stators 202 in FIG. 17 are shown as of identical constructioncomparable to stator 25 as already described, and each cooperates withits complementary rotor face 211 or 212 in similar manner. This doubleended rotor cooperating with two stators offers not only double theworking capacity for a small increase in housing size, but also theadvantage that with the rotor splined or otherwise mounted for freeaxial movement on its drive shaft 215, as shown, it can float betweenthe two stators as required to balance the hydraulic pressure conditionsbetween each pair of complementary working surfaces, and thereby toeliminate axial thrust on the shaft 215 and its supporting bearings (notshown). It will also be apparent that the rotor 200 can be provided ateach end thereof with an end cap like and for the same purpose as theend cap 35.

FIG. 18 shows a double ended rotor 220 of the reverse configuration fromrotor 200 in that it has a cylindrical portion 222 of minimum diameterat its middle portion and frusto-conical working portions 221 and 223 atopposite ends thereof, each of these working portions having its sectionof maximum diameter at the outer end of the rotor body, and the threesections being secured together as by bolts 224. The two stators 225 inFIG. 18 correspond to stators 202 in FIG. 17 but are arranged in theopposite manner for proper cooperation with the complementary workingsurfaces of the rotor 220.

The housing 230 in FIG. 18 includes an inlet chamber 231 locatedgenerally centrally and having an inlet port 232, and there aredischarge chambers 233 and 234 adjacent opposite ends of the rotor 220and each having a discharge port 235. The rotor 220 includes a pair ofcircumferential flanges 237 which correspond in function to the end cap35 to block tramp metal and the like from access to the resulting entryslots to the spaces between the working surfaces of the rotor andstators, and it is for this reason that the rotor is made in threeportions for installation with the stators 225. It will also be apparentthat the rotor 220 can float on its supporting shaft 238 in the samemanner, and with the same advantages, as described for the rotor 200 inFIG. 17.

FIG. 19 shows a fragment of a rotor 240 wherein the two rows of pockets241 are milled to an essentially arcuate contour in axial section,rather than the relatively flat bottoms of the pockets shown in theother views, and cooperate with lands 242. The stator 245 has two rowsof similar milled pockets 246 and lands 247. Except for their contour inaxial section, the pockets 241 and 246 should substantially conform tothe geometry described above in connection with FIG. 8, and thisconfiguration of pocket can be used in any of the other embodiments ofthe invention disclosed herein.

FIG. 20 shows a fragment of a rotor 250 having a working face composedof multiple pockets 251 and a circumferential frusto-conical land 252.As shown, the bottom 253 of each pocket 251 is essentially parallel inaxial section with the face of the rotor, so that the angle defined bythe pocket bottom and the axis of the rotor is the same as angle a inFIG. 8. The stator 255 is of complementary construction, with itsworking face comprising pockets 256 and a land 257, and with the pocketbottom 258 essentially parallel with the rotor pocket bottom 253. Thesepockets accordingly conform with the overall geometry ranges noted abovein connection with FIGS. 6 and 8, and this pocket configuration could beused in any of the other forms of the invention already described.

While the forms of apparatus herein described constitute preferredembodiments of the invention, it is to be understood that the inventionis not limited to their precise forms of apparatus, and that changes maybe made therein without departing from the scope of the invention. It isalso to be understood that use of the apparatus of the invention is notlimited to the treatment of paper making stock, and that the apparatusmay be used for the defibering or deflaking of other liquid slurrystocks, for example in the processing of tobacco.

What is claimed is:
 1. Apparatus for defibering liquid slurry stocks,comprising:a. a housing defining a chamber having an inlet port and anoutlet port adjacent opposite ends thereof, b. an annular stator mountedwithin said chamber between said ports and having a frusto-conicalinternal working face with the smaller end thereof adjacent said inletport, c. a rotor mounted in said housing for rotation within said statorand having a frusto-conical working face complementary to and alignedwithin said stator face, d. each of said working faces having therein atleast one circumferential row of angularly spaced pockets separated byaxially extending land areas, e. each of said pockets in said rotorhaving generally axially extending side walls and a generally radiallyextending back wall cooperating with portions of said land areas on saidrotor face to form a circumferential land, .Iadd.f. each of said rotorpockets having a bottom wall extending from said back wall thereof tothe surface of said rotor whereby said back wall constitutes the onlyend wall of said pocket, .Iaddend. .[.f..]. .Iadd.g. .Iaddend.each ofsaid pockets in said stator having generally axially extending sidewalls and a generally radially extending front wall cooperating withportions of said land areas on said stator face to form acircumferential land, .[.and.]. .Iadd.h. each of said stator pocketshaving a bottom wall extending from said front wall thereof to thesurface of said stator whereby said front wall constitutes the only endwall of said pocket, and .Iaddend. .[.g..]. .Iadd.i. .Iaddend.the axialdimensions of said pockets and of said rotor and stator being ofpredetermined relationship locating said circumferential lands thereonin axially staggered relation with each other and in radially opposedrelation with said stator and rotor pockets respectively to force thestock to travel back and forth between said pockets in flowing from saidinlet port to said outlet port.
 2. Defibering apparatus as defined inclaim 1 further comprising means on said smaller end of said rotorforming an annular skirt of greater outer diameter than the innerdiameter of the adjacent end of said stator face and cooperatingtherewith to define a radially outwardly opening circumferential entryslot to the front ends of said rotor pockets and thereby to minimize theaccess of high specific gravity materials to said pockets.
 3. Defiberingapparatus as defined in claim 2 wherein said chamber is of greater innerdimensions than the outer dimension of said stator in a planeperpendicular to the axis of said rotor to provide an annular spacetherein surrounding the adjacent ends of said rotor and stator forcollection of high specific gravity contaminant materials, and meansforming a cleanout port from said space.
 4. Defibering apparatus asdefined in claim 1 wherein each of said working faces on said rotor andstator include two circumferential rows of said angularly spaced pocketsand land areas separated by a second circumferential land, and whereinthe axial dimensions of said pockets and of said rotor and stator are ofpredetermined relationship locating all of said circumferential landsthereon in axially staggered relation with each other and in radiallyopposed relation with said stator and rotor pockets respectively toforce the stock to travel back and forth between said rotor and statorpockets in flowing from said inlet port to said outlet port. 5.Defibering apparatus as defined in claim 4 further comprising means onsaid smaller end of said rotor forming an annular skirt of greater outerdiameter than the inner diameter of the adjacent smaller end of saidstator face and cooperating therewith to define a radially outwardlyopening circumferential entry slot to the front ends of said rotorpockets and thereby to minimize the access of high specific gravitymaterials to said pockets.
 6. Defibering apparatus as defined in claim 5wherein said pockets in the row adjacent the smaller end of each of saidrotor and stator are larger in circumferential and/or axial extent thansaid pockets in the row adjacent the larger end thereof, and whereinsaid row of pockets adjacent the larger end of each of said rotor andstator contains a greater number of said pockets than said row adjacentthe smaller end thereof.
 7. Defibering apparatus as defined in claim 4wherein said row of pockets adjacent the larger end of each of saidrotor and stator contains a greater number of said pockets than said rowadjacent the smaller end thereof.
 8. Defibering apparatus as defined inclaim 4 wherein .Iadd.at least one of the circumferential and axialdimensions of .Iaddend.said pockets in the row adjacent the smaller endof each of said rotor and stator .[.are larger in circumferential and/oraxial extent than.]. .Iadd.is larger than the corresponding dimension of.Iaddend.said pockets in the row adjacent the larger end thereof. 9.Defibering apparatus as defined in claim 8 wherein said row of pocketsadjacent the larger end of each of said rotor and stator contains agreater number of said pockets than said row adjacent the smaller endthereof.
 10. Defibering apparatus as defined in claim 4 wherein one-halfthe total included angle of each of said working faces is an angle (a)in the range of 15° to 75°, the angle (d) included by said side walls ofeach of said pockets is in the range of 0° to 60°, and the angle (c)defined by each of said back and front walls of said pockets and theaxis of said rotor is greater than said angle (a) but is not greaterthan 120°.
 11. Defibering apparatus as defined in claim 4 whereinone-half the total included angle of each of said working faces is anangle (a) in the range of 20° to 30°, the angle (d) included by saidside walls of each of said pockets is in the range of 3° to 15°, and theangle (c) defined by each of said back and front walls of said pocketsand the axis of said rotor is greater than said angle (a) but is notgreater than 90°.
 12. Defibering apparatus as defined in claim 4 whereineach of said pockets has a bottom wall extending generally parallel withthe axis of said rotor to provide each of said pockets with asubstantially greater radial depth adjacent said radially extending wallthereof than at the opposite end thereof, and wherein one-half the totalincluded angle of each of said working faces is an angle (a) in therange of 15° to 75°, the angle (d) included by said side walls of eachof said pockets is in the range of 0° to 60°, the angle (c) defined byeach of said back and front walls of said pockets and the axis of saidrotor is greater than said angle (a), but is not greater than 120°, andthe angle (b) defined by each of said bottom walls and said rotor axisis smaller than said angle (c) and greater than 0°.
 13. Defiberingapparatus as defined in claim 12 wherein said angle (a) is in the rangeof 20° to 30°, said angle (d) is in the range of 3° to 15°, said angle(c) is at least 30° but not greater than 90°, and said angle (b) is inthe range of 3° to 6°.
 14. Defibering apparatus as defined in claim 1wherein .Iadd.said bottom wall of .Iaddend.each of said pockets .[.has abottom wall extending.]. .Iadd.extends .Iaddend.in such angular relationwith the axis of said rotor as to provide each of said pockets with asubstantially greater radial depth adjacent said radially extending wallthereof than at the opposite end thereof.
 15. Defibering apparatus asdefined in claim 14 wherein one-half the total included angle of each ofsaid working faces is an angle (a) in the range of 15° to 75°, the angle(d) included by said side walls of each of said pockets is in the rangeof 0° to 60°, the angle (c) defined by each of said back and front wallsof said pockets and the axis of said rotor is greater than said angle(a) but is not greater than 120°, and the angle (b) defined by each ofsaid bottom walls and the said rotor axis is smaller than said angle (c)and greater than 0°.
 16. Defibering apparatus as defined in claim 1wherein the edges of each of said land areas on said rotor aresymmetrical with respect to the axis of said rotor, and furthercomprising reversible drive means for said rotor whereby each of saidedges can operate selectively as the leading edge of said land area. 17.Defibering apparatus as defined in claim 1 wherein said inlet port islocated on the side of said housing, and further comprising a removableclosure on said housing forming the wall of said chamber opposite saidrotor and stator, means accessible upon removal of said closure forremovably mounting said rotor and stator in operative position, and saidrotor and stator being proportional for removal and replacement throughthe opening exposed by removal of said closure.
 18. Defibering apparatusas defined in claim 1 wherein one-half the total included angle of eachof said working faces is an angle (a) in the range of 15° to 75°, theangle (d) included by said side walls of each of said pockets is in therange of 0° to 60°, and the angle (c) defined by each of said back andfront walls of said pockets and the axis of said rotor is greater thansaid angle (a) but is not greater than 120°.
 19. Apparatus fordefibering liquid slurry stock, comprising,a. a housing defining aninlet chamber having an inlet port and an outlet chamber having anoutlet port, b. an annular stator mounted within said housing betweensaid chambers and having an internal working face, c. a rotor mounted insaid housing for rotation within said stator on a substantiallyhorizontal axis and having a working face complementary thereto anddefining therewith an annular working zone connecting said chambers, d.one end of said rotor projecting through and beyond the adjacent end ofsaid stator face into said inlet chamber, e. means on said rotor endforming an annular skirt of greater outer diameter than the innerdiameter of the adjacent end of said stator face and cooperatingtherewith to define a radially outwardly opening circumferential entryslot to said working zone and thereby to minimize the access of highspecific gravity materials to said zone, and f. means including a portbelow said rotor end for effecting removal of such high specific gravitymaterials.
 20. Defibering apparatus as defined in claim 19 wherein saidstator has a frusto-conical internal working face with the smaller endthereof adjacent said inlet chamber, said rotor has a frusto-conicalworking face complementary to and aligned within said stator face, andthe smaller end of said rotor is of smaller diameter than the adjacentend of said stator face and projects axially therethrough into saidinlet chamber.
 21. Defibering apparatus as defined in claim 19 furthercomprising baffle means comprising a generally vertical annularpartition positioned within said inlet chamber between said inlet portand said rotor with the openings therethrough located generally in linewith the axis of said rotor to trap high specific gravity materialsentering said inlet port below said opening on the inlet side of saidpartition and thereby to prevent access thereof to said working zone.22. Apparatus for defibering liquid slurry stock, comprising:a. ahousing defining an inlet chamber having an inlet port and an outletchamber having an outlet port, b. an annular stator mounted within saidhousing between said chambers and having an internal working face, c. arotor mounted in said housing for rotation within said stator on asubstantially horizontal axis and having a working face complementarythereto and defining therewith an annular working zone connecting saidchambers, and d. baffle means comprising a generally vertical annularpartition positioned within said inlet chamber between said inlet portand said rotor with an opening therethrough located generally in linewith the axis of said rotor to trap high specific gravity materialsentering said inlet port below said opening on the inlet side of saidpartition and thereby to prevent access thereof to said working zone.23. Defibering apparatus as defined in claim 22 wherein said bafflemeans also comprises means in the space on the inlet port side of saidpartition for directing stock entering through said inlet port to alevel below said opening prior to flow therethrough to said workingzone. .Iadd.
 24. Working elements for use in apparatus for defiberingliquid slurry stocks which includes a housing defining a chamber havingan inlet port and an outlet port adjacent opposite ends thereof,comprisinga. an annular stator element having a frusto-conical internalworking face and adapted to be mounted within said chamber between saidports with the smaller end thereof adjacent said inlet port, b. a rotorelement having a frusto-conical working face complementary to saidstator face and adapted to be mounted in said housing for coaxialrotation with said stator element, c. each of said working faces havingtherein at least one circumferential row of angularly spaced pocketsseparated by axially extending land areas, d. each of said pockets insaid rotor element having generally axially extending side walls and agenerally radially extending back wall cooperating with portions of saidland areas on said rotor face to form a circumferential land, e. each ofsaid rotor pockets having a bottom wall extending from said back wallthereof to the surface of said rotor whereby said back wall constitutesthe only end wall of said pocket, f. each of said pockets in said statorelement having generally axially extending side walls and a generallyradially extending front wall cooperating with portions of said landareas on said stator face to form a circumferential land, g. each ofsaid stator pockets having a bottom wall extending from said front wallthereof to the surface of said stator whereby said front wallconstitutes the only end wall of said pocket, and h. the axialdimensions of said pockets and of said rotor and stator elements beingof predetermined relationship locating said circumferential landsthereon in axially staggered relation with each other and in radiallyopposed relation with said stator and rotor pockets respectively toforce the stock to travel back and forth between said pockets in flowingfrom said inlet port to said outlet port. .Iaddend. .Iadd.
 25. Workingelements for use in defibering apparatus as defined in claim 24 whereinsaid bottom wall of each of said pockets extends in such angularrelation with the axis of said rotor element as to provide each of saidpockets with a substantially greater radial depth adjacent said radiallyextending wall thereof than at the opposite end thereof. .Iaddend..Iadd.
 26. Working elements for use in defibering apparatus as definedin claim 25 wherein one-half the total included angle of each of saidworking faces is an angle (a) in the range of 15° to 75°, the angle (d)included by said side walls of each of said pockets is in the range of0° to 60°, the angle (c) defined by each of said back and front walls ofsaid pockets and said rotor axis is greater than said angle (a) but isnot greater than 120°, and the angle (b) defined by each of said bottomwalls and said rotor axis is smaller than said angle (c) and greaterthan 0°. .Iaddend. .Iadd.
 27. Working elements for use in defiberingapparatus as defined in claim 24 wherein one-half the total includedangle of each of said working faces is an angle (a) in the range of 15°to 75°, the angle (d) included by said side walls of each of saidpockets is in the range of 0° to 60°, and the angle (c) defined by eachof said back and front walls of said pockets and the axis of said rotorelement is greater than said angle (a) but is not greater than 120°..Iaddend. .Iadd.
 28. Working elements for use in defibering apparatus asdefined in claim 24 wherein each of said working faces on said rotor andstator elements includes two circumferential rows of said angularlyspaced pockets and land areas separated by a second circumferentialland, and wherein the axial dimensions of said pockets and of said rotorand stator elements are of predetermined relationship locating all ofsaid circumferential lands thereon in axially staggered relation witheach other and in radially opposed relation with said stator and rotorpockets respectively to force the stock to travel back and forth betweensaid rotor and stator pockets in flowing from said inlet port to saidoutlet port. .Iaddend. .Iadd.
 29. Working elements for use in defiberingapparatus as defined in claim 28 wherein said row of pockets adjacentthe larger end of each of said rotor and stator elements contains agreater number of said pockets than said row adjacent the smaller endthereof. .Iaddend..Iadd.
 30. Working elements for use in defiberingapparatus as defined in claim 28 wherein at least one of thecircumferential and axial dimensions of said pockets in the row adjacentthe smaller end of each of said rotor and stator elements is larger thanthe corresponding dimension of said pockets in the row adjacent thelarger end thereof. .Iaddend. .Iadd.
 31. Working elements for use indefibering apparatus as defined in claim 30 wherein said row of pocketsadjacent the larger end of each of said rotor and stator elementscontains a greater number of said pockets than said row adjacent thesmaller end thereof..Iaddend..Iadd.
 32. Working elements for use indefibering apparatus as defined in claim 28 wherein one-half the totalincluded angle of each of said working faces is an angle (a) in therange of 15° to 75°, the angle (d) included by said side walls of eachof said pockets is in the range of 0° to 60°, and the angle (c) definedby each of said back and front walls of said pockets and the axis ofsaid rotor element is greater than said angle (a) but is not greaterthan 120°. .Iaddend. .Iadd.
 33. Working elements for use in defiberingapparatus as defined in claim 28 wherein one-half the total includedangle of each of said working faces is an angle (a) in the range of 20°to 30°, the angle (d) included by said side walls of each of saidpockets is in the range of 3° to 15°, and the angle (c) defined by eachof said back and front walls of said pockets and the axis of said rotorelement is greater than said angle (a) but is not greater than 90°..Iaddend. .Iadd.
 34. Working elements for use in defibering apparatus asdefined in claim 28 wherein each of said pockets has a bottom wallextending generally parallel with the axis of said rotor element toprovide each of said pockets with a substantially greater radial depthadjacent said radially extending wall thereof than at the opposite endthereof, and wherein one-half the total included angle of each of saidworking faces is an angle (a) in the range of 15° to 75°, the angle (d)included by said side walls of each of said pockets is in the range of0° to 60°, the angle (c) defined by each of said back and front walls ofsaid pockets and the axis of said rotor element is greater than saidangle (a), but is not greater than 120°, and the angle (b) defined byeach of said bottom walls and said rotor axis is smaller than said angle(c) and greater than 0°. .Iaddend..Iadd.
 35. Working elements for use indefibering apparatus as defined in claim 34 wherein said angle (a) is inthe range of 20° to 30°, said angle (d) is in the range of 3° to 15°,said angle (c) is at least 30° but not greater than 90°, and said angle(b) is in the range of 3° to 6°. .Iaddend.